Microtelephone.



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Wli'NESSESI v 1 ""INVENTOR: 4 flazz ez;

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Patnted Sept. 30,1913.

' To all whom it may concern UNITED S ATES PATENT FFICE.-

WILLIAM B. OLIVER, OF COLLINGS'WOOD, NEW JERSEY, ASSIGNO R TO OLIVER ELEC- -'JIRIC COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPGRATION OF PENN- SYLVANIA.

MICROTELEPHONE.

Specification of Letters Patent.

Patented Sept. 30, 1913.

Application filed July 27, 1909. Serial No. 509,858..

Be it known that I, VILLIAM OLIVER, of Collingswood, in the county of Camden and State of New Jersey, have invented certain new and useful Improvements in companying drawings.

. resents a front view 'of the external casing The primary use for which my invention is intended, is to assist the defective hearing of persons more or less afflicted with deafness, butobviou'sly, the device is susceptible of other uses, which require a transmitting element having the following characteristics,-great sensitiveness, susceptibility for extremely minute regulation, high power of magnifying sound, and capacity for so modifying the behavior of the diaphragm electrode as to damp or eliminate vibrations of-a certain character. As a result of these various features, it may be said that the device has the capacity for controllably selecting and amplifying certain sound vibrations, while minimizing others.

Referring to the drawings, Figure I, repof. the instrument in a preferred embodiment thereof. Fig. II, is a vertical central section through the casing and the instru- -ment proper, on the line II, II, of Fig. I. Fig. III, is a front view, in elevation, of

the diaphragm electrode, indicating certain damping devices mounted. thereon. Fi IV, is a vertical transverse section throug the casing and the instrument proper, on the line IV, IV, of Fig. II. Fig, V, is a view of the spring support for the main rear electrode. Fig. VI, is a sectional view on an enlarged scale, through one of the pockets in the main rear electrode, showing the con tents thereof and one of the adjustable secondary rear electrodes, which constitutes the bottom of said pocket. Fig. VII, is a View, partly in section and partly in elevation, of

amodified form of the internal casing, the

external casing being similar tothat shown 'in Fig. I. Fig. VIII, is a front view of the internal casing represented in Fig. VII.

I first describe -the micro-telephone element which may be termed the transmitter, without reference to the particular form of casing, external or internal, which may be used in connection therewith.

The main support or housing 1, is of 'ing bushings 4, and the backing plate being also insulated from the housing by means of an annular washer 5. The spring support 6, 0f the main rear electrode, rests against the'inner face of the backing plate 2, said support being dish-shaped, and, as shown in Fig. V, provided with a plurality of radial slots '7, which permit relatively free springaction. The raised central portion,

' which is flat, is perforated by a plurality of holes, in this instance, six in number, arranged symmetrically asshown in Fig. V. The main rear electrode 10, consists of a relatively-massive disk shaped block of carbo-n, having'a central hole terminating "in an enlarged cavity 13, for the reception of avnut 14, which is prevented from turning therein, said nut engaging ascrew 15, which passes through the central hole of the electrode 10, and of the spring support 6, and has a slotted head received within a countersunk opening in the center of the backing plate 2.; By' turning this screw in one-direction, the main rear electrode 10, can be drawn upward toward the backing plate 2, against the tension of the spring support 6, and, by turning .the screw in the opposite direction, the resiliency of the spring support 6, will cause the main rear electrode to move away from the backing plate. Thus the main rear electrode can be adjusted, throughout a relatively large range of movement, toward or from the diaphragm or front electrode 22. By this arrangement I effect what may be termed'the coarse adjustment of the electrodes. I

The main rear electrode 10, is provided with a plurality of countersunk conical re- Cesses or pockets 11, in thisinstance five in number, symmetrically grouped around the central cavity 13, in registry with the, holes 8, of the spring support. Said pockets are filled with small carbon balls or granules 12. These balls or granules are of a diameter greater than the distance between the adjacent faces of the front and rear electrodes, so that the balls or granules are retained inposition by the rims of theirrespective pockets, and are not permitted to escape into the interspace betweenthe' PIOXlj mate faces of the main, front and rear electrodes. 1 1

Referring to the enlarged view of Fig. VI, it will be seen that from the bottom of each pocket 11, a cylindrical hole 19, extends entirely through the main rear electrode. The opening of each hole is closed r by means of a cylindrical carbon plug 20, mounted upon the end of a screw 18, whose threads. run freely within the hole 19, and

the registering outer -hole 8, of the spring support, but engage with a threaded registering, hole in the backing plate. 2. The end of the carbon plug 20, thus constitutes the bottom surface-of the pocket, and by rotating the screw 18, the plug may be made to move toward or from the front diaphragm 10. These carbon plugs constitute what may be termed the secondary rear electrodes, in

that while they form a portion of the rear electrode as a whole, (being electrically in communication with the block 10), they are independently adjustable toward or from the diaphragm, so that the carbon balls or against the front face of the housing 1, in electrical contact therewith, and is rovided with a washer 23,'placed beneath t esurface of a protecting diaphragm 24, these parts being clamped in position by means of the annular cap 25, which screws upon the exterior face, of the housing 1, and overlaps the front IV. The protecting diaphragm 24, is prefedge as shown inthe sectional view of Fig.

erably constructed of mica or thin celluloid, and it may'have perforations 28, 'as shown, or maybe entirely imperforate if desired.

I prefer to mount upon the front face of the diaphragm, or front electrode '22,

- damping devices, whose eneralchara'cter I have indicated in Fi II One form there'- of is a very thin lea en disk 45, cemented or otherwise secured to the diaphragm, 22.

Other forms are exceedin ly light metallic" springs46, 47, having dis s of some material, such as fiber, which is not a conveyer of sound vibrations, interposed between them and the electrode, said springs bearing very lightly against the protecting diaphragm 24. In commercially constructed telephones, damping springs have been employed to modify theyibrations of the diaphragm, but in micro-telephones of the present character, the extreme delicacy of the vibrations to be transmitted, prohibits the use of externally supported damping necessary to mount the damping devices directly upon the diaphragm electrode itself, and to make them of such character as not only to be mechanically susceptible of this mounting, but as not to coarsen the damping efi'ec I The transmitter, is of course, to be included within an electric circuit, the connections being conveniently made as follows :The insulated conducting wire 35, enters through the hole 36, in the wall of the housing, and is connected with a clip 37, carried by the screw 38, so arranged with relation to the non-conducting bushing 4, and washer 5, respectively, as to be insulated from the backing plate, but electrically connected with the housing, which inturn is in electricaL contact with the front electrode 22. The other conducting wire 39, enters through the hole 36, and is attached to a clip 40, in circuit with the backing plate 2,,and, through the spring support 6, with the main and secondary rear electrodes 10, and 18, respectively, but

is insulated from the housing 1, by means of the bushing-4, and washer 5. The device thus'described constitutes a complete microtelephone transmitter, and may be used without the external casing if desired, since the diaphragm 24, protects the front electrode from injury. When,'however,:high

sound-magnifying power is desired, I employ the external casing, shown in Figs. I, and II, which comprises the cylindrical cup-shaped shell 30, of such dimensionsas to leave a free space'around and behind the instrument. The front portion of the shell-is provided with an annular cap 31, fitting frictionally upon the rim thereof and-extending radially inward to a distance of about one-third of'the radius of the external periphery of the casing. The casing is secured to the backing plate by means of screws 33, or in any convenient manner.

In the arrangement shown in Figs. VII, and VIII, the external casing, corresponding to the parts 30, and 31 s of the same configuration, but the protecting diaphragm 42, is preferably made of relatively heavy metal, ascompared with the light celluloid or mica diaphragm 24, and, instead of being a flat'disk, is dished outwardly in approximate conformity with the cross-section of the cap 31. The protecting diaphragm 42,

screws directly upon the housing 1, an annular washer 41, intervening between the front electrode 43, and the periphery of the diaphragm 42. I

Ignoring for the present the'external cas .ing, it willflbe' noted that the instrument pockets in the rear electrode are adjustable toward and from the front electrode, enables me to attain the exact intimacy of contact between the front electrode and the carbon balls, or granules, which is mosteflicient in any particular instrument, or best adapted to the requirements of any particular person whose defective hearing is to be remedied, the contents of each pocket being also individually adjustable, and they may be therefore filled with different sizes of balls or granules and the proper degreeof contact pressure insured.

When the instrument is employed-as an ad unct to defective hearing this suscepti-- bility of minute regulatioii is of peculiar value, slnce mere loudness of sound is not the only factor .in assisting the hearing, it

i being found that some persons. can best hear sounds ofa peculiar character not directly dependent upon loudness. This characteristic of the instrument is also enhanced by the employment of damping devices directly mounted upon the front electrode, which result in eliminating certain overtones. When however, the transmitter is employed with the external casing, and particularly that form shown in Figs. 'VII, and VIII, other highly valuable characteristics are found to exist, these may be briefly described as follows It is-intended that the sound waves-from any givensource shall be received, in the first instance, upon the thin carbon diaphragm, which'is presented in the direction of their approach, and hence I have applied the term front electrode thereto, as indicating the contemplated position of that element with relation to the source from which the sound waves emanate.

- The force of the waves is modified by the protecting diaphragm 24, or 42. -As however, the housing 1, is notarrangcdin contact with the casing 30, a definite passageway exists, through. which sound waves, after being deflected around the front edge of the internal casing, and to act forwardly; against the backing 5 plate 2. This backing plate directly carries trode 10. The pressuredue to the impingement of the sound waves, is therefore cumucan pass to the rearlative :that is to say, it acts directly upon trode, and that the motion of the sound waves is also transmitted inthe same direction to the rear electrode, so that to a certain extent, the front and rear electrodes tend to move in unison, under the impingement of any given wave. Hence the microphonic effect is due to the differential movement of the two electrodes, in approximately'the same direction at the same time.

In my invention, the arrangement, whereby direct access of sound waves to the rear face of the rear electrodes is attained, tends to produce a movement thereof in opposition to the movement of the front electrode so that although t9 some extent, the normal vmovement of the two electrodes in unison may tend to occur, the movement of the rear one is opposed by the movement due to approach from the opposite direction. Hence, 'instead of a differential movement in the same direction, the extent whereof is determined by the'relative mass and positions of the two electrodes alone, I am' enabled to "obtain a cumulative effect, due to movements in opposite directions, or to a reduction of the attempt of the rear electrode to move in unison with the front one. The result is a great intensificat-ionof the microphonic action, and a very marked increase in the vol 'ume of the sound.

I believe that the above explanation accounts for the fact that such practical increase in the volume and cl earness of the sound occurs, when my above described arrangement is used, but I do not however, de-

sire'it to be understood asmaking this thecry a part of the essence of my invention. --Furthermore, I have found that the microphonic action is improved by the'interposition of the annular shield formed by the cap 31-, which partly closes the front of the inence thereof, toward or from the rear elec- I strument. The most advantageous extent thereof being that above stated, a. e. the projection being about one-third of the total radius. This fact seems to be in harmony V -with the explanation above given, in that the shield tends to prevent the direct impingeinent of sound wavesupon the housing, and adjacent parts, and tends to limit such direct impingement to the central portion of the front electrode, so that their transmission to the rear electrodes through the housing itself is modified, while at the same time, the passage to the'rear of the instrument is main tamed and the current of-sound wavesfiows of the rear electrode.

I am of course aware that in certain microphone transmitters an"-'Ienlarged'- casmg around it to exerttheir effect upon the back has beenprovided'so as to afford quite an' extended area forthe collection of sound, and that while the central portion of such casing has been closed by a solid backing,

openings have been formed at ornear the periphery to convey the sound waves around toward the rear portion of the casing. In

such instrumentdhowever, the diaphragm,

which I have termed the front electrode, is placed at the rear of the instrument, so that the sound waves collected by the enlarged periphery are receivedby a diaphragm electrode facing in the opposite direction to that from which the Waves are supposed to emanate. This arrangement bears no resemblance to the organization which -I have describedfand lacks the capacity for pi pducing the cumulative action above set 'orth. This feature: of my invention, I therefore believe to be characteristic and absolutely novel, and while its peculiar method of operation is enhanced, by the other features which I have described relating to the adjustability of the electrodes I do not desirethe source of sound, and have applied the correlative term main rear electrode as a convenient one to describe the relatively massive carbon electrode WhlCh, under the I conditions mentioned, is more remote from the spurce' .of sound; the term secondary rear electrode having been employed to indicate the fact that the carbon granules may be appropriately considered as constituting a part of the rear electrode in contra-distinction to the frontone. since however, the terms f front and rear when thus generall}? used, may be ambiguous for the purposes of distinguishing the invention from trans- 'mitters of the prior art, I- -have thought it best, in certain of the claims,whereinafter made, to refer to the element heretofore called the front I electrode, as a diaphragm electrode, andto'the element heretofore termed the mainrear electrode, as

I a carbon block electrode, the term relatively massive, being employedio further characterize the said block electrode in comparison with the relatively thin diaphragm electrode. I also employ the term transnutter as synonymous with the transmitting element of a micro-telephone. I also employ the term. granules ascomprehensive of, the. small movable carbon elements, forming part of theyariable electric circult,

, whethertheybe in ball form or otherwise.

j I claim:--

1. In a transmitter, the combination of a diaphragm electrode; a relatively massive carbon block electrode provided with pockets; carbon granules arranged within said pockets; aspringmounting for the carbon block electrode, sai'd'spring normally tending to press said carbon block electrode toward said front electrode; and an adjusting screw, adapted to retract said rear electrode agalnst the tension of the spring mounting,

and-to permit-movement in the opposite direction under the'resiliency of said mountin a In a transmitter, the combination of a diaphragm electrode; a relatively massive carbon block electrode provided with pockets; carbon granules arranged within said pockets and 'inelectrical connection with each other, whereby together with said carbon block electrode they formv art of one electrical circuit; and means orvarying the depth of said pockets, whereby adjustment of the pressure of the carbon granules may be effected without varying the position of the carbon block electro e with relation to' thediaphragm electrode.

3. Ina transmitter, the,combination of a diaphragm electrode; a relatively massive carbon block electrode; I carried by said carbon block electrode; means for varying'the adjustment of said carbon block electrode with relation to said diaphragm electrode; means for varying the adjustment of the carbon granules with relationto said diaphragm electrode.

4. In a transmitter, diaphragm electrode;

carbon granules and independent I the combination of a a relatively massive carbon block electrode, provided with a opening at the, bottom ranules arranged within on plug arranged within pocket having an thereof; carbon said pocket; a car said opening; and shifting-saidplug.=' I v v 5. In a transmitter, the combination of a diaphragm electrode; a relatively: massive carbon block electrode havinfg;-

at the bottom; and plugs i or closin bottoms of said' pockets; said plugs mounted independently of said carbon block electrode, whereby'said carbon block trode and said plugs 'may respond differently to sound waves. a Y

. 6., In a transmitter,

the

a variable electric circuit therethrough; a spring ca'rried by said diaphragm electrode; and a nonvibratory pad inserted between said spring and said electrode, substantially as set forth.

means for controllably pockets open electhe combination'of a diaphragmelectrode; means for completing.

' 7. In a transmitter, the combination with a. front diaphragm electrode and a rear relatively massive carbon block electrode; of means whereby the direct impingement of sound waves upon the front surface of the diaphragm electrode is permitted, while the direct transmission of said Waves to the front surface of the carbon block, electrode is minimized; and means whereby other sound waves are conveyed to impinge upon the rear surface of the carbon block electrode, substantially asset forth. I

8. In a transmitter, the combination of a. front diaphragm electrode; a relatively massive rear carbon block' electrode havi'ng pockets; carbon granules carried by said pockets; a mounting plate for said carbon block electrode arranged at the rear thereof; and a deflecting shell provided with a passage way around said diaphragm electrode, and leading to said mounting'plate, whereby the direct trans ssion of sound vibrations .to the front 0 the carbon block is minimized andsaid carbon block electrode is permitted to respond mainly to vibrations impinging from the rear.

' 9. In a transmitter, the combination of a front diaphragm electrode; a relatively massive rear carbon block electrode containing pockets; carbon granules in said pockets; a mounting plate for said carbon block electrode arranged at the rear thereof; and

an inclosing shell having a reduced opening at the front and provided with a passage Way leading around said diaphragm to the rear of said mounting plate whereby the direct transmission of sound vibrations to the front of the carbon block electrode is Vania, this twenty-sixth day of July, 1909.

, WILLIAM B. OLIVER. W'itnessesf J AMES H. BELL,

E. L. FULLERTON. 

